A growing body of experimental evidence suggests that, on the whole, we know significantly less about our friends, colleagues, and even spouses than we think we do. This lack of knowledge extends far beyond embarrassing game-show fodder – we’re often completely wrong about their likes and dislikes, their political beliefs, their tastes, their cherished values. We lowball the ethics of our co-workers; we overestimate how happy our husbands or wives are.

Also really interesting is this sentence: “Work by William B. Swann of the University of Texas and Michael J. Gill of Lehigh University has looked at dating couples and pairs of college roommates and found that, while their confidence in the accuracy of their knowledge of each other increased the longer the two had known each other, their actual accuracy didn’t appreciably improve.” Interesting.